implement parallel invocation of tox environments tox-dev#439

docs/changelog/439.feature.rst

@@ -0,0 +1,2 @@
+``tox --parallel`` now allows running tox environments in parallel. ``--parallel-live`` allows showing the live output of the standard output and error. Note that parallel evaluation
+ disables standard input. Use non parallel invocation if you need standard input. By :user:`gaborbernat`.

src/tox/config.py

@@ -274,7 +274,9 @@ def parse_cli(args, pm):
         print(get_version_info(pm))
         raise SystemExit(0)
     interpreters = Interpreters(hook=pm.hook)
-    config = Config(pluginmanager=pm, option=option, interpreters=interpreters, parser=parser)
+    config = Config(
+        pluginmanager=pm, option=option, interpreters=interpreters, parser=parser, args=args
+    )
     return config, option
 
 
@@ -413,6 +415,15 @@ def tox_addoption(parser):
         dest="sdistonly",
         help="only perform the sdist packaging activity.",
     )
+    parser.add_argument(
+        "--parallel", action="store_true", dest="parallel", help="run tox environments in parallel"
+    )
+    parser.add_argument(
+        "--parallel-live",
+        action="store_true",
+        dest="parallel_live",
+        help="connect to stdout while running environments",
+    )
     parser.add_argument(
         "--parallel--safe-build",
         action="store_true",
@@ -822,7 +833,7 @@ def __call__(self, parser, namespace, values, option_string=None):
 class Config(object):
     """Global Tox config object."""
 
-    def __init__(self, pluginmanager, option, interpreters, parser):
+    def __init__(self, pluginmanager, option, interpreters, parser, args):
         self.envconfigs = OrderedDict()
         """Mapping envname -> envconfig"""
         self.invocationcwd = py.path.local()
@@ -831,6 +842,7 @@ def __init__(self, pluginmanager, option, interpreters, parser):
         self.option = option
         self._parser = parser
         self._testenv_attr = parser._testenv_attr
+        self.args = args
 
         """option namespace containing all parsed command line options"""
 
@@ -1133,6 +1145,7 @@ def make_envconfig(self, name, section, subs, config, replace=True):
 
     def _getenvdata(self, reader, config):
         candidates = (
+            os.environ.get("_PARALLEL_TOXENV"),
             self.config.option.env,
             os.environ.get("TOXENV"),
             reader.getstring("envlist", replace=False),

src/tox/session.py

@@ -568,6 +568,14 @@ def subcommand_test(self):
                     venv.envconfig.setenv[str("TOX_PACKAGE")] = str(venv.package)
         if self.config.option.sdistonly:
             return
+        if self.config.option.parallel:
+            self.run_parallel()
+        else:
+            self.run_sequential()
+        retcode = self._summary()
+        return retcode
+
+    def run_sequential(self):
         for venv in self.venvlist:
             if self.setupenv(venv):
                 if venv.envconfig.skip_install:
@@ -581,9 +589,49 @@ def subcommand_test(self):
                         self.installpkg(venv, venv.package)
 
                 self.runenvreport(venv)
-                self.runtestenv(venv)
-        retcode = self._summary()
-        return retcode
+            self.runtestenv(venv)
+
+    def run_parallel(self):
+        """here we'll just start parallel sub-processes"""
+        live_out = self.config.option.parallel_live
+        args = [sys.executable, "-m", "tox"] + self.config.args
+        try:
+            position = args.index("--")
+        except ValueError:
+            position = len(args)
+        try:
+            parallel_at = args[0:position].index("--parallel")
+            del args[parallel_at]
+            position -= 1
+        except ValueError:
+            pass
+
+        tox_runs = {}
+        for venv in self.venvlist:
+            env = os.environ.copy()
+            env["_PARALLEL_TOXENV"] = venv.envconfig.envname
+            args_sub = list(args)
+            if hasattr(venv, "package"):
+                args_sub.insert(position, str(venv.package))
+                args_sub.insert(position, "--installpkg")
+            stdout, stderr = (None, None) if live_out else (subprocess.PIPE, subprocess.PIPE)
+            run = subprocess.Popen(args_sub, env=env, stdout=stdout, stderr=stderr)
+            tox_runs[venv.name] = (venv, run)
+
+        to_finish = set(tox_runs.keys())
+        while to_finish:
+            for name in set(to_finish):
+                venv, run = tox_runs[name]
+                res = run.poll()
+                if res is not None:
+                    venv.status = "skipped tests" if self.config.option.notest else res
+                    if not live_out:
+                        out, err = run.communicate()
+                        venv.out = out
+                        venv.err = err
+                    to_finish.remove(name)
+            if to_finish:
+                time.sleep(0.1)
 
     def runenvreport(self, venv):
         """

tests/unit/session/test_parallel.py

@@ -0,0 +1,33 @@
+import os
+
+
+def test_parallel_live(cmd, initproj):
+    initproj(
+        "pkg123-0.7",
+        filedefs={
+            "tox.ini": """
+            [tox]
+            envlist = a, b
+            [testenv]
+            commands=python -c "import sys; print(sys.executable)"
+        """
+        },
+    )
+    result = cmd("--parallel", "--parallel-live")
+    assert result.ret == 0, "{}{}{}".format(result.err, os.linesep, result.out)
+
+
+def test_parallel(cmd, initproj):
+    initproj(
+        "pkg123-0.7",
+        filedefs={
+            "tox.ini": """
+            [tox]
+            envlist = a, b
+            [testenv]
+            commands=python -c "import sys; print(sys.executable)"
+        """
+        },
+    )
+    result = cmd("--parallel")
+    assert result.ret == 0, "{}{}{}".format(result.err, os.linesep, result.out)